- set_BaggingDate() allows time_t now

- set_BagSize() uses unsigned long int now

- renamed create_new() to add_payload()
- added add_bagmetadata()
- added add_fetchfile()
- added add_othertags()
- using default values in Bag-constructor
- enhanced example create_a_bag.cpp

- validate() checks for at least one checksum file

- added testcass

- renamed has_oxum() to has_PayloadOxum()
- renamed get_bagmetadata() to get_metadata()
- renamed has_bagmetadata() to has_metadata()

- fixed order for tagmanifest call in store()

- check null ptr for payload in validate()

- using const for paths

- added get_all_bag-files() to bag

- implemented constructor
- implemented get_entries()
- implemented fetch_all_entries()
- implemented store()